General Inherited operations and associations

Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 29

6.6.2 Inherited operations and associations

CV_DiscreteCurveCoverage Figure 8 inherits the association CoverageFunction and the operations locate, find, list, evaluate and evaluateInverse from CV_DiscreteCoverage, with the restriction that the associated CV_GeometryValuePairs and those returned by the operations shall be limited to CV_CurveValuePairs. Figure 8 — CV_DiscreteCurveCoverage

6.7 CV_CurveValuePair

CV_CurveValuePair is the subtype of CV_GeometryValuePair that has a GM_Curve as the value of its geometry attribute.

6.8 CV_DiscreteSurfaceCoverage

6.8.1 General

A discrete surface coverage is a coverage whose domain consists of a collection of surfaces. In most cases, the surfaces that constitute the domain of a coverage are mutually exclusive and exhaustively partition the extent of the coverage. Surfaces or their boundaries may be of any shape. The boundaries of component surfaces often correspond to natural phenomena and are highly irregular. EXAMPLE A coverage that represents soil types typically has a spatial domain composed of surfaces with irregular boundaries. Any set of polygons can be used as a spatial domain for a discrete surface coverage. Spatial domains composed of congruent polygons are very common. Often, these domains are composed of congruent rectangles or regular hexagons. The geometry of such a tessellation may be described in terms of a quadrilateral grid 8.2 or a hexagonal grid 9.1. The spatial domain of a discrete surface coverage may also consist of the triangles that compose a TIN 10.7, or the polygons of a Thiessen polygon network 7.1. Copyright © 2007 Open Geospatial Consortium, Inc. All Rights Reserved. 30 Figure 9 — CV_DiscreteSurfaceCoverage

6.8.2 Inherited operations and associations

CV_DiscreteSurfaceCoverage Figure 9 inherits the association CoverageFunction and the operations locate, find, list, evaluate, and evaluateInverse from CV_DiscreteCoverage, with the restriction that the associated CV_GeometryValuePairs and those returned by the operations shall be limited to CV_SurfaceValuePairs.

6.8.3 TINBase

The association TINBase may be used to link a CV_DiscreteSurfaceCoverage to a CV_TINCoverage 10.2. The constraint discreteTIN.element.geometry = triangleSource.controlValue.geometry requires that the spatial domain of the CV_DiscreteSurfaceCoverage be composed of the triangles belonging to the CV_TINCoverage.

6.8.4 ThiessenBase

The association ThiessenBase may be used to link a CV_DiscreteSurfaceCoverage to a CV_ThiessenPolygonCoverage 7.2. The constraint discreteThiessen.element.geometry = polygonSource.controlValue.geometry requires that the spatial domain of the CV_DiscreteSurfaceCoverage be composed of the polygons belonging to the CV_ThiessenPolygonCoverage.